What are Marmorkrebs?

“Marmorkrebs” is an informal name given to marbled crayfish that were discovered by hobbyists in Germany in the late 1990s. “Marmorkrebs” roughly translates from German as “marbled crab.” The scientific name for Marmorkrebs is Procambarus virginalis (previously Procambarus fallax f. virginalis). They are an asexual relative of slough crayfish (Procambarus fallax) that live across Florida and southern Georgia in the United States. There are no known native populations of Marmorkrebs in North America; the only known cases of them in the wild are where they have been introduced by humans.

Marmorkrebs are parthenogenetic: they are all females, and reproduce without sex. This is the only decapod crustacean found that reproduces only this way, giving it incredible potential as a model organism for research. Some of the advantages of Marmorkrebs are that they are genetically identical, reproduce at high rates, and are easy to care for.

Marmorkrebs are also an invasive species. They have been introducted in many places, and have established populations in at least many countries, damaging agriculture and threatening native species. Marmorkrebs should not be used for bait (see here), kept in outdoor tanks or ponds (Marmorkrebs can migrate over land; see here), or placed in any other situation where they could be released into natural ecosystems. In North America, Marmorkrebs are prohibited in Missouri (since 2011) and Tennessee (since 2015). The European Union banned possession, trade, transport, production, and release of Marmorkrebs (and several other crayfish species) in 2016.

Laws

Missouri has added Marmorkrebs to its prohibited species list, effective 1 March 2011. Read more here. Tennessee designated Marmorkrebs as “Class V wildlife,” meaning they can only be kept by zoos, effective October 2015. Read more here and here.